Impairments of spinal and extremity range of motion occur as sequelae to Parkinson's disease (PD) and contribute significantly to difficulties with balance. While subtle impairments of balance may not be obvious on routine clinical examination, they clearly are present early in the disease when appropriately evaluated. If diagnosed early in the disease process, impairments of balance can be remediated with exercise, delaying functional limitations. Coupled with functional retraining, exercise may improve overall physical functional ability and quality of life. Additionally, patients with mild PD have been found to have poor economy of movement during walking. Improvements of economy of movement have not been evaluated with exercise; it is likely that improved range of motion and balance will improve economy of movement. This investigation will examine whether: (1) balance, functional abilities and quality of life improve with improvements of spinal range of motion and balance; (2) physical intervention improves economy of movement, (3) general aerobic conditioning improves functional ability; (4) exercise targeting impairments associated with PD (e.g., range of motion and balance) is more effective than general endurance training and both are more effective than 'standard-of-care' treatments; (5) an ongoing home program, following a supervised exercise program, maintains increased spinal range of motion, balance, and functional ability. The proposed study is a randomized clinical trial, with 3 treatment arms and 4 repeated measures (before and after treatment, with follow-up at 10 and16 months). Specifically we will compare usual care based on a booklet provided by the American Parkinson Foundation, general endurance training, and PD specific flexibility and functional training. The primary outcomes (4 and 10 months) are measures of: (1) overall functional ability (Continuous-Scale Physical Functional Performance test; (2) balance, (Functional Reach); and (3) economy of movement (rate of oxygen consumption at a set walking speed, [(O2 consumption]). We postulate that PD-targeted flexibility and functional training will improve physical functional ability, in part, by improving balance & walking economy. Further, we expect the PD-specific targeted intervention to be more effective than general endurance training or 'standard-of-care' at improving overall physical function.